1. Field of the Invention
The present invention relates to a flexible pipe joint system for supplying desired fluids to apparatus and devices which involve up and down or to and fro type reciprocal movement.
2. Description of the Prior Art
Flexible pipe joints as illustrated in FIGS. 4a and 4b have been used in order to enable operations including up and down or to and fro movements, for example, the movement of the press heating plate in the manufacture of fancy plywood used in furniture or desks for business use, which movement is up and down with respect to a raw material plywood (laminated veneer with a synthetic resin plate superimposed thereon) set on the stand of the press machine while supplying steam to the press heating plate, or the movement of the burner in the case of combustion of fuel in boilers of thermal power stations in accordance with changes in demand for electricity, which movement is toward the nozzle while supplying a fuel and steam to the burner and backward leaving the burner while interrupting the supply of the fuel and the like.
More specifically, the known pipe joint includes three swivel joints a, i.e., those arranged on both sides and in the center, and two arm pipes b connecting the three swivel joints to each other. The respective swivel joints a include a stepped cylinder body 1 with a larger diameter portion 1a having an open end and a smaller diameter portion 1b serving as a pipe connection portion for connecting a pipe, the smaller diameter portion 1b of the central swivel joint a being bent substantially at right angles, an elbow pipe 2 having a ball portion 2a with a semispherical surface and with increasing diameter like a funnel shape at one end thereof (lower end in FIG. 4a) and also having a bent portion 2b at another end which is bent substantially at right angles and serving as a pipe connection portion for connecting a pipe, and a cap nut 3 which can be engaged with the larger diameter portion 1a with threads. Inside the larger diameter portion 1a of the cylinder body 1 is inserted the ball portion 2a of the elbow 2 and is fitted snugly using an annular gasket 4 which has an inner surface, arcuate in cross section, permitting contact with the surface of the ball portion 2a. On the other hand, a coil spring 5 and a washer are arranged in a central portion of the larger diameter portion 1a of the cylinder body which urges the elbow 2 outward to cause the spherical surface of the ball portion 2a to be pressed against the arcuate (in cross section) inner surface of the gasket 4, thus airtight sealing the cylinder body 1 and the elbow 2a as well as permitting their rotary and rocking actions.
One arm pipe b is inserted at its ends into the pipe connection portion 2b of the elbow 2 of the swivel joint a on one side (on the left hand side in FIG. 4a) and into the pipe connection portion 2b of the elbow 2 of the swivel joint a, respectively, and welded thereto while another arm pipe b is inserted at its ends into the bent smaller diameter portion 1b of the swivel joint a in the center and into the pipe connection portion 2b of the elbow 2 of the swivel joint on the other side (on the right hand side in FIG. 4a), respectively, and welded thereto. Further, an inlet pipe P.sub.1 is attached to the smaller diameter portion 1b of the cylinder body 1 of the swivel joint a on one side to establish fluid communication with a fluid source (not shown) and on the other hand, an outlet pipe P.sub.2 is attached to the smaller diameter portion 1b of the cylinder body 1 of the swivel joint a on the other side to connect it to an acting member such as a press plate or a burner. As indicated in dashed line in FIG. 4b, the two pipes b are bent to permit up and down (vertical) or to and fro (horizontal) movement of the acting member while supplying fluid thereto.
While in the above-described conventional pipe joint system, the diameter (D in FIG. 2) of the spherical surface of the ball portion 2a of the elbow 2 of each swivel joint a is made larger than the inner diameter (d.sub.1 in FIG. 2) of the upright wall of the gasket 4 and the inner diameter (d.sub.2 in FIG. 2) of the edge flange of the cap nut 3 so as to prevent the coming out of the elbow 2 from the cylinder body 1 due to the pressure of the fluid contained in the inside thereof, and therefore, in need of exchanging the gasket 4 because of the wear or deformation thereof, the gasket 4 and the cap nut 3 cannot be withdrawn from the ball portion 2a of the elbow 2 by simply screwing back the cap nut from the cylinder body 1 when the respective swivel joints a are connected with each other by means of the arm pipes b, that is, when in use. Therefore, the portions connecting the elbow 2 to the arm pipe b must be separated from each other before exchanging the gasket 4 with a new one, which is inconvenient. This not only causes decrease in the precision of the size accompanied by fusing and re-welding but also is uneconomical.